This application claims the priority of German Application No. 199 10 331.3, filed Mar. 9, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method for initially filling a fuel system in the case of a motor vehicle having at least two operating elements as well as a fuel pump delivering the fuel.
For the pre-filling of a fuel system in the case of a motor vehicle after its manufacturing process, it is necessary to trigger the fuel pump for several seconds. This triggering is conventionally caused by a bridging of the fuel pump relay.
It is also known to trigger the engine timing unit to operate the fuel pump by way of a tester. The tester is connected externally and issues a diagnostic command.
However, during or after the manufacturing of the vehicle, the above-mentioned methods require certain application and setup expenditures which cause additional costs.
With respect to related documents, reference is made to German Patent document DE 32 46 658 A1, in which a device is described for starting and switching-off motor vehicle engines having automatic transmissions.
It is an object of the present invention to provide a method and apparatus by which the first filling of the fuel system can take place in a simple manner and at reasonable cost.
This object is achieved by a method for pre-filling a vehicle fuel system. The vehicle has at least two operating elements as well as a fuel pump for delivering the fuel. By the simultaneous actuation of the at least two operating elements existing in the vehicle, an operation of the fuel pump is triggered for filling the fuel system.
Accordingly, in the case of the method of the invention, at least two operating elements already present in the vehicle are actuated simultaneously. As the result of this actuation, an operation of the fuel pump is triggered for filling the fuel system, particularly for filling the fuel lines.
Suitable operating elements are, for example, the accelerator pedal and the brake pedal. However, as an alternative, other combinations of operating elements existing in the vehicle can also be selected. The decisive fact is only that no additional equipment has to be used for triggering the first filling. Additional setup costs can therefore be avoided.
In the case of conventional engines, a microprocessor-based engine timing unit is preferably provided in which the above-described method can be implemented by means of software. If electric control commands are already used in the case of the corresponding operating elements (for example, for the accelerator pedal and the brake pedal), the method according to the invention can be implemented at no cost via a purely software solution.
Preferably, it should be possible to operate the fuel pump only when the ignition is switched on and/or when the engine is switched off. This prevents an unintentional filling from taking place in a preceding vehicle production step, for example, when the vehicle is almost completely assembled and the accelerator pedal and the brake pedal are operated unintentionally and simultaneously.
Another measure for preventing an unintentional filling when the accelerator pedal and the brake pedal are selected as operating elements is provided in that the fuel pump is operated only if the accelerator pedal and the brake pedal respectively are completely depressed.
Since the present case relates to an initial or pre-filling of a motor vehicle, the inventive activation of the fuel pump during the entire life of the vehicle should be possible only a limited number of times, particularly only once. As an alternative, the activation of the fuel pump may be permitted only in a defined range of operating hours or kilometers. As another alternative, the fuel pump can be activated only once during a driving cycle.
If only a limited number of such fuel fillings are provided, a reset possibility can be provided so that the possibilities of the fuel filling can also be utilized after or during a stay in a repair shop.
So that the fuel pump will not be triggered for an unnecessarily long time, a limiting of the triggering time of the fuel pump is preferably provided (for example, 20 seconds).
In order to prevent a dry operation of the fuel pump, it should preferably not be possible to operate this fuel pump as long as no fuel flows around it. In the case of a fuel pump arranged in the fuel tank, the filling of the fuel tank can be checked for this purpose by means of a sensor. As an alternative, it is possible to monitor the operating data of the fuel pump. For example, on the basis of its current consumption or its rotational speed, conclusions can be drawn concerning a dry operation.
In addition, a pump advance is to be prevented, which is generally carried out in the case of an xe2x80x9cignition onxe2x80x9d signal. For this purpose, the fuel pump operation can be blocked for as long as there is no first filling. To this extent, the present method for the first filling acts like an initialization.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.